This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 4 |
| 2 | 28 |
| 3 | 128 |
| 4 | 480 |
| 5 | 1600 |
| 6 | 4928 |
| 7 | 14336 |
| 8 | 39936 |
| 9 | 107520 |
| 10 | 281600 |
| 11 | 720896 |
| 12 | 1810432 |
| 13 | 4472832 |
| 14 | 10895360 |
| 15 | 26214400 |
| 16 | 62390272 |
| 17 | 147062784 |
| 18 | 343670784 |
| 19 | 796917760 |
| 20 | 1835008000 |
| 21 | 4198498304 |
| 22 | 9550430208 |
| 23 | 21609054208 |
| 24 | 48653926400 |
| 25 | 109051904000 |
| 26 | 243403849728 |
| 27 | 541165879296 |